the science of the artificial reef program

The Science Behind Volusia County’s

Artificial Reef Program

Scrawled Cowfish Lactophrys quadricornis

Photo by: Frank Alvarez

Definition of an Artificial Reef:According to US Code, (a compilation and codification of the general and permanent Federal Laws1) “(*) The term “artificial reef” means a structure which is constructed or placed in water covered under this chapter for the purpose of enhancing fishery resources and commercial and recreational fishing opportunities.” 33 U.S.C. § 2105(1) 2012

US Code Title 33 – Navigational and Navigable Waters Chapter 35 – Artificial Reefs

Section 2105. Definitions

(*) Title 1 of the Code as published by the office of the Law Revision Counsel

*It is important to note that other definitions exist depending on which user group (i.e. scientist, engineer, fisher) is associated with the definition.

Why Build Artificial Reefs?According to the 2007 National Artificial Reef Plan published by the

National Oceanographic and Atmospheric Administration:

“Increasing demands on fish stocks by both commercial and recreational fishermen and losses of benthic habitat due to development, fishing pressure, and pollution, have had substantial effects on many reef-associated fish species.” [1]

Benefits of Artificial Reefs To Volusia

County1. Creates habitat for plants, invertebrates and fishes in an otherwise featureless area of little interest to divers or fishers.In an ecological sense it creates surface area that allows encrusting organisms to attach and grow on the reef. This creates a food source for other organisms and also a place to hide from larger predators that are attracted to the reef for food, i.e. fish and lobsters. Spiny Lobster Panulirus

argus

Photo Courtesy Volusia County Reef Research Dive Team.

Benefits of Artificial Reefs To Volusia County

2. Utilizes materials that would otherwise take up space in landfills. Such bulky materials are recycled as Artificial Reef Materials.

Artificial Reef Material being loaded onto a barge for deployment at Site 12.

Materials for building artificial reefs must meet standards published in “Guidelines For Artificial Reef Materials” by the Atlantic and Gulf States Marine Fisheries Commissions. [2]

Photo Courtesy Joe Nolin, County of Volusia


3. Reduces fishing pressure on Natural Reefs.Creating new artificial reefs reduces fishing pressure by providing more quality areas to fish. [3] In Volusia County, artificial reefs are created approximately 10-15 miles inshore of most of its natural reef system, providing easier access to fishers and divers.

Goliath Grouper Ephinephelus itajaraPhoto Courtesy Volusia County Reef Research Dive Team.

Benefits of Artificial Reefs To Volusia County4. Increases biomass of Volusia County’s

offshore environment.Expanding the surface area of offshore habitats using artificial reefs increases the biomass of benthic organisms significantly. [4]

Biomass – the mass of living biological organisms in a given area or ecosystem.

The encrusting organisms and associated invertebrates attract fish to the structure, providing food for smaller reef dwelling fishes as well as places to hide. Larger predators are attracted to the additional food source.


Productivity relies on the assumption that there is a generation of biomass over time. [5] This may be true for plants and encrusting organisms that grow and live on the reef full time, but is harder to prove for fishes that move from reef to reef searching for food.


5. Increases Productivity of Volusia County’s offshore environment???

The question becomes do artificial reefs just attract fishes from other areas or do artificial reefs actually lead to the production of more fishes. This question remains to be answered. [6]

6. Positive Socioeconomic Impacts. Artificial Reefs increase economic activity in local areas in the form of expenditures, incomes and jobs.

Such benefits also increases the value to non-user groups who see the creation of artificial reefs as beneficial to the environment and community. Such support helps justify future public expenditures on artificial reefs. [7]

Sinking of the Antilles Star at Site 4 on 6/29/04.



The offshore habitat in Volusia County differs from the offshore habitat in Southern Florida where natural reefs are much closer to shore. The creation of inshore artificial reefs in Volusia County makes the reefs more accessible to fishers and divers with limited monetary resources.

Benefits of Artificial Reefs To Volusia County7. Increases the scientific and research

opportunities in Volusia County. Artificial Reefs increase scientific and research opportunities that can provide technical information to help reef managers and fishery biologists make good policy decisions.

Photograph of Site 11 culvert after 1 year of growth.


Volusia County lies at the border between the Tropical and Temperate Climate Zones which creates a geographically interesting area of tropical and temperate species.

Characterizing Volusia County’s Offshore

Environment

http://www.webquest.hawaii.edu/kahihi/sciencedictionary/C/climatezone.php

Volusia County’s Offshore Habitat Is Heavily Influenced By The Gulf Stream

The Gulf Stream is a warm water current that starts in the Straights of Florida and moves up the coast of Florida and East Coast. The warm, clear waters provide nutrients necessary for coral reefs to grow.

Notice how it hugs the Florida Coastline in the south and moves offshore as it follows the Continental shelf.

Volusia County’s Proximity To The Gulf

StreamPonce Inlet is on average 42 miles from the western edge of the Gulf Stream.

29 N

80 W

Photos courtesy Rutger’s Coastal Ocean Observation

Lab

A distinct difference occurs in the continental shelf between South Florida and Volusia County’s offshore environment. This is evident during this reconstruction of Florida during the last glacial period. [8]

http://academic.emporia.edu/aberjame/student/lairdl/qgeology.html

The increased area of continental shelf in Volusia County allows for a separation between artificial and natural reefs sites. Characterizing the offshore habitat helps reef managers design and plan artificial reefs and fisheries management policies.

Chart showing shelf breaks, sea mounts and natural reefs of Volusia County.

Natural reefs in green

Shelf breaks

Sea mounts

Chart courtesy Halifax Sport Fishing Club

Volusia County’s Natural ReefsVolusia County’s Natural Reefs are characterized by having lower relief than natural reefs in South Florida. Diving conditions are less consistent (visibility) than the more favorable conditions found farther south where the Gulf Stream is closer to shore and shallow water (Traci Grubbs, personal communication, 18 October, 2012).Photo courtesy Joe Knott, Location: East

Ridge

Caribbean Reef Octopus, Octopus briareus

South Florida’s Natural ReefsSouth Florida’s Natural Reefs are characterized by having higher relief and a greater diversity of species. Diving conditions are more favorable where the Gulf Stream is closer to shore and provides a more consistent water temperature (Joe Knott, personal conversation, 21 October,2012).

Photo courtesy Lee Wahler

Location : West Palm Beach, FL

Designing Artificial ReefsThe design of artificial reefs is critical to

effectively meet the requirements of targeted species and support community

structures. Therefore, their design must consider the purposes of the reef, the specifications of the environment, and what fisheries applications must be meet. [9]

Photo Credit : Steve Spring

Removal of tires from a failed artificial reef project, Broward

County (2006).

http://www.xray-mag.com/files/tire_reef1.jpg

Materials SelectionArtificial Reef Materials are selected to meet the primary goal of a reef project while taking into consideration cost and availability. [3]


Materials SelectionGuidelines for Artificial Reef Materials are outlined by the Atlantic and Gulf States Marine Fisheries Commissions. [3]

Criteria For Selecting Materials

1. Function – the ability to attract and hold aquatic organisms

2. Compatibility (with environment) – materials must be evaluated to determine what risks there are to the environment, i.e. leaching of hazardous chemicals

3. Durability – materials must be resistant to the harsh chemical and physical forces of the marine environment

4. Stability – materials must be stable enough to remain in its original configuration and permitted site

Materials SelectionConcrete, made from Portland Cement, is composed primarily of lime, a component of limestone. Limestone is sedimentary rock made up of the skeletal remains of marine creatures including corals. These features make it an excellent habitat for settlement and growth of encrusting organisms. [3]

Photo courtesy Larry Bell, Reef Site 5

Materials Selection

Benefits of Using Concrete:1. Can be recycled secondary material2. Extremily compatible with the marine environment3. Durable – “Based on the 32 to 34 year performance

observations…All concretes exhibited a high level of durability in seawater exposure” (Portland Cement Association, per communication) [3]

4. Stable – heavy enough to stay in position5. The flexibility to cast in a variety of forms6. Excellent habitat for encrusting organisms

Drawbacks of Using Concrete:7. Heavy – need heavy equipment to handle, making it

dangerous to haul and deploy at sea8. Tendency to sink into softer substrates [3]

Materials SelectionSteel-Hulled Ships are especially popular with divers. In 2003 the FWC held 487 vessels as artificial reefs in their database. This constituted ~ 25% of public artificial reef records. [3]


200’ barge before

deployment in 2011. Notice large holes cut out for diver and large fish access.

Materials Selection

Benefits of using Steel-Hulled Ships:1. Make interesting dive locations2. Durable – may last 60+ years3. Produce high vertical profile – this attracts transient

pelagic fishes as well as demersal fishes (feed on or near the bottom)

4. Reuse may be more economical than scrapping5. Vessels, under certain conditions, provide habitat for

spawning aggregations of certain managed fishes such as groupers and amberjack. [3]Antilles Star before sinking, site 4, 6-29-

2004


Materials Selection

Drawbacks of using Steel-Hulled Ships:• Expensive to clean and remove of hazardous materials.• Vessels typically provide less shelter for demersal fishes.• Steel-hull surface is less favorable for colonization of epibenthos than concrete or rocks.• Vessels may be more prone to damage and movement during hurricanes and large storms.• Maintaining adequate navigational clearance can be a challenge in shallower waters. [3]

Photo Courtesy Larry Bell

Materials SelectionDesigned Structures specifically used for artificial reefs have increased in popularity. This trend develops as reef managers and scientists research different design structures to improve artificial reef effectiveness. [10]

Red Snapper swimming

around a Reef Ball at Site 1.

Materials SelectionBenefits of Using Designed Structures:1. Can be designed to meet specific goals of an Artificial

Reef Program, i.e. targeting species, life stages, scientific studies, etc.

2. Designed structures can be constructed as needed, therefore decreasing the reliance on secondary materials.

3. Can be constructed to fit the criteria of reef materials, including durability, stability, and compatibility with marine organisms.

4. Design flexibility to maximize characteristics such as complexity, hole size, and number of holes to meet the specific goal of the study or project.

Drawbacks of Using Designed Structures:5. Heavy – need heavy equipment to handle making it

dangerous to haul and deploy at sea6. Tendency to sink into softer substrates [3]

Design of Reef StructureThe effectiveness of artificial reefs depends on the design of the reef structure, specifically whether meets the habitat requirements of its targeted species. [11] If the purpose of artificial reefs is to improve fisheries management, then this is one of the most important considerations.

Jackknife Fish school around a culvert at Site 11.

Jacknife Fish, Equetus lanceolatus

Reef SizeSeveral studies have shown that reef size significantly

influences biomass, total number of species, diversity of species, and fish density. [12][13] A few trends have been proposed with a significant amount of research to support them.

Site 4 photo with extensive coral

and other epibenthic

growth.

Photo Courtesy Volusia County Reef Research Dive Team

Larger reefs may have higher biomass densities (including invertebrates, algae, and fishes, etc), but may be composed of fewer, but larger fishes. This may be due to the success of larger individuals through competition and predation of smaller fishes, including juveniles. [12]

Reef size

Smaller Reefs may have an increased density of fishes (aggregated closer together) as well as a greater diversity of fish species than larger reefs. [14][12]

Reef Size

Multiple Smaller Reefs have been shown to provide more fish biomass and diversity than a larger reef of equal area and volume . [14]

Reef size

Margins between smaller reef units increases the availability of soft bottom food sources [15] and also increases transitional zones between reef and open seafloor.

Considerations of Depth In Reef Construction1. User Considerations – depth is an important

consideration to making reefs accessible to fishers and divers

Deeper Depths are farther from shore, making it more challenging to divers (due to increased currents, reduced sunlight, and lower temperatures), and require more fuel to reach the destination.

Purplemouth Moray


2. Biological ConsiderationsPhysical properties vary with depth that affect the

biological properties of a reef at depth.

Depth Light Pressure Current Temperature (at bottom)

Deeper reefs can have stronger currents that deliver more larvae for settlement (invertebrate and fishes), supply more planktonic food for residents, and can scour more of the bottom (remove sand layer) that provide more hard bottom and therefore more available space for growth. [16]

Carolina Hake, Urophycis earllii, at Site 4, notice the hard growth on the substrate indicating scouring of the bottom.


Kruer and Causey (1992) compared natural and artificial reefs at varying depths for two years and concluded that natural reefs showed an increase in species diversity and total numbers with increased depth, but that artificial reefs showed an increase in numbers at shallower depths (14m compared to 24m). They attributed the increase in numbers at the shallower site to increased scouring. [17]

Biological Considerations

Srinivason (2003) stated that fine-scale factors vary with depth that make it difficult to separate influences and differences of depth. [18]

An Oyster Toadfish, Opsanus tau, camouflaged

to resemble growth on the artificial reef. Photo Courtesy Volusia County Reef Research Dive

Team

Referring back to designing artificial reefs to attract your targeted species. It is not always the targeted species, but the forage base (prey items) that must be considered. For example, recruitment of grunts provides an excellent forage base for larger piscivorous fishes such as groupers and snappers. [16]


Inshore sites provide excellent habitat for

Tomtates, Haemulon aurolineatum, which feed

on small, bottom dwelling

invertebrates.


Release Mortality Rates


Studies show a relationship between survival and capture depths. Shallower depths have shown an increased chance of release survival. [19]

These studies also point out many factors that affect release survival rate.


Release Mortality Rates

These studies point out that many factors affect survival rate including:• Capture depth• Venting• Retrieval Rate• Hook Type – circle hook vs. J-hook• Surface to depth temperature difference• Presence of surface predators• Handling – proper release techniques• Hook location – relevant to hook type [20]

Fisheries Management depends the survival rate of commercially and recreationally important species.

Reef Height and Profile Increased Profile increases upwelling

that provides planktonic food source to smaller,

schooling fishes. (Hayward Mathews, personal communication,

11 March, 2013)

This, in turn, attracts larger transient fishes such as King Mackerel and Amberjack.

Reef Complexity / Shelter

One way to increase carrying capacity and biomass of artificial reefs is to provide shelter from predation to its inhabitants. [21]

“The use of a mixture of different kinds of materials of different sizes and void spaces in irregular piles facilitates creation of a complex cavity network of small interconnected chambers which appear to provide benefits for many fish species – both predators and prey – that may find features that suit their specific requirements.” [22]

The use of large artificial reef units provide little refuge for juvenile and smaller fishes important to the reef’s overall health.

Studies suggest that the variation in habitat type and size created by artificial reefs removes some factors (environmental bottlenecks) that may affect productivity. The increase in complexity may have positive impacts on fish abundance, species richness, and diversity. [23]

A decrease in juvenile to

adult succession

could lead to an

environmental bottleneck

A Seaweed Blenny hides amongst artificial reef growth.


Habitat Complexity is important to juvenile reef fish and invertebrate survival.



Arrow Crabs and Damsels

forage around a head of

Oculina coral.

Natural reef complexity is also formed by extensive epibenthic growth on the reef.

One study found 20,000 individual organisms living among the branches of 42 small Oculina colonies, including 230 species of mollusks, 50 species of crabs, 47 species of amphipods (small crustaceans), 21 species of echinoderms, and numerous other groups of organisms. [24]


Artificial Reef PermittingThe U.S. Army Corp of Engineers (ACOE) is responsible for

the construction and maintenance of artificial reefs in federal waters. [25] Local coastal governments undergo a lengthy permit process that can last 12 months.Permits within State Waters are fulfilled by the ACOE and the Florida Department of Environmental Protection. [26]

A typical Volusia County Artificial Reef is permitted as 1 square mile.

Deposits are usually 2/10 of a mile apart.

Typical arrangement of deposits

Subsequent deposits will start to fill in spaces.

Artificial Reef ConstructionExtreme care must be taken during the

construction phase of creating artificial reefs.• Deposits must be deployed within a specific permitted site.• Weather conditions must be carefully monitored because of

the large, heavy load being transported to the site.• Loading the barge is a safety concern while preparing to

haul concrete culverts and materials.• Deploying materials at thesite is also a huge safety concern.• The sinking of steel-hulledvessels is conducted by cuttingholes at the water line and then pumping water into the vessel.

Preparing the barge for a deployment of materials to site 4.

Succession Of Artificial ReefsTypically, algae and invertebrates colonize new reef

structure rapidly, but the biomass and species diversity changes drastically until an equilibrium is reached several years later. [27]

Dominant species change, through competition, over the succession of a new reef. Eventually an equilibrium is reached where the benthic biomass and species diversity remains somewhat constant.Fouling organisms, such as this Red Encrusting Sponge, provide a complex habitat that is preferred by more complex organisms such as corals. [28]


Monitoring Artificial ReefsMonitoring artificial reefs is conducted by the Volusia County

Reef Research Dive Team

Monitoring the locations, biological activity, and seasonal differences is very important to maintaining permitted sites and gauging the overall health of the reef site. These parameters are recorded using Diver Survey Forms. Changes before and after reef equilibrium is meet are documented through the use of these reef survey forms.Survey Forms are recorded then analyzed and stored in Volusia County. This data is also shared with “Reef Environmental Education Foundation” (REEF). The data is loaded into REEF's online database, where a variety of reports can be created on species diversity, distribution, and population trends. This can be accomplished for a specific reef or large geographic region.

http://news.nationalgeographic.com/news/2011/03/pictures/110404-sharks-lionfish-alien-fish-invasive-species-science/

Solving User ConflictsConflicts between user groups can be very

detrimental to an Artificial Reef program.Recommendations To Help Solve User Conflicts:• Common courtesy is key to sharing the reef areas.

Everyone has access to reef areas and these areas should be shared with equal respect.

• Communication – use your VHF radio to communicate with other boats about their activities, intentions, and estimated time remaining on the site.

• Follow safe “Diver Down” Regulations. If you approach within 300 feet of a “Divers Down Flag”, you must approach no faster than necessary to maintain headway. Diving is inherently dangerous and following this rule closely is very important to being respectful to divers.

• If an area is being fished, avoid diving that deposit or communicate openly with the fishermen to gauge their openness to diving that area.

• Designate different sites for preferred usage, i.e. fishing, underwater photography, spearfishing.

Solving User Conflicts• Increase reef sites to dilute user concentrations and conflicts.• Organize meetings between user groups to open

communication and problem solve issues. Conflicts between user groups at sea could be lessened by familiarity between groups.

http://www.loscabosguide.com/monalisacharters/index.html

http://scuba.about.com/od/divemedicinesafety/tp/Dive-Flags.htm

References[1] National Oceanic and Atmospheric Administration (2007). National Artificial Reef

Plan (as Amended): Guidelines for Siting, Construction, Development, and Assessment of Artificial Reefs. Silver Spring, Maryland, United States Department of Commerce: vii, 1-54.

[3] Leeworthy, V. R., T. Maher, et al. (2006). Can Artificial Reefs Alter User Pressure On Adjacent Natural Reefs? Bulletin of Marine Science 78(1): 29-37.

[2] Lukens, R. R. and C. Selberg (2004). Guidelines for Marine Artificial Reef Materials: Second Edition. Ocean Springs, Miss. and Washington, D.C., Gulf and States Marine Fisheries Commissions. January 2004: 198 pages.

[5] Allaby, Michael. A Dictionary of Ecology. 3rd ed. Oxford, UK: Oxford University Press. 2006. Print.

[4] Sampaolo, A. and G. Relini (1994). Coal Ash For Artificial Habitats in Italy. Bulletin of Marine Science 55 (2-3): 1277-1294.

[6] LIndberg, B. (2010). "Understanding the Ecology of Artificial Reefs: No Simple Answers." Sea grant Florida: 1-4.

[7] Adams, C., B. Lindberg, et al. (2006). The Economic Benefits Associated with Artificial Reefs. Gainesville, Florida, IFAS, University of Florida: 6.

[8] Laird, Patrick. Reconstruction of the Florida Coast During the Late Wisconsin Glaciation. Emporia State University. 20 November 2004. Web. 28 November 2012.

[9] Pratt, J.R. (1994). Artificial Habitats and Ecosystem Restoration: Managing For the Future. Bulletin of Marine Science 55 (2-3): 268-275.

[10] Grove, R.S., C.J. Sonu, and M. Nakamura. (1991). Design and Engineering of Manufactured Habitats for Fisheries Enhancement. pp. 109 -152. In Artificial Habitats for Marine and Freshwater Fisheries. W. Seaman and L. Sprague, editors.

[11] Pickering, H. and D. Whitmarsh (1997). Artificial Reefs and Fisheries Exploitation- A Review of the “Attraction Versus Production" Debate, the Influence of Design and Its Significance for Policy. Fisheries Research 31: 31-59.

[12] Bohnsack, J. A., D. E. Harper, et al. (1994). Effects of Reef Size on Colonization and Assemblage Structure of Fishes at Artificial Reefs off Southeastern Florida, U.S.A. Bulletin of Marine Science 55(2-3): 796-823.

[13] Bombace, G., G. Fabi, et al. (1994). Analysis of the Efficacy of Artificial Reefs Located in Five Different Areas of the Adriatic Sea. Bulletin of Marine Science, 55 (2-3): 559-580. [14] Ambrose, R.F., S. Swarbrick. (1989). Comparison of Fish Assemblages on Artificial and Natural Reefs Off the Coast of Southern California. Bulletin of Marine Science, 44(2): 718-733.[15] Frazer, T. K. and W. J. Lindberg (1994). Refuge Spacing Similarly Affects Reef-associated Species. Bulletin of Marine Science 55(2-3): 388-400.

[16] Sherman, R.L., D. Gilliam, R. Spieler (1999). A Preliminary Examination of Depth Associated Spatial Variation in Fish Assemblages On Small Artificial Reefs. Journal of Applied Ichthyology 15: 116-121.

[17] Kruer, C.R., L. Causey, (1992). The use of large artificial reefs to enhance fish populations at different depths in the Florida Keys. Florida Keys Artificial Reef Association, Inc.[18] Srinivasen, M. (2003) Depth Distribution of Coral Reef Fishes: The Influence of Microhabitat Structure, Settlement, and Post-Settlement Processes. Oecologia, 137(1) : 76-84.[19] Gitschlag, G.R., M. Renaud, (1994) Field Experiments on Survival Rates of Caged and Released Red Snappers. North American Journal of Fisheries Management 14: 131-136. [20] Rummer, J.L. Factors Affecting Catch and Release (CAR) Mortality in Fish: Insight into CAR Mortality in Red Snapper and the Influence of Catastrophic Decompression. American Fisheries Society Symposium 60: 113-132.

[21] Bohnsack, J. A. (1989). Are High Densities of Fishes at Artificial Reefs the Result of Habitat Limitation or Behavioral Preference. Bulletin of Marine Science 44(2): 631-645.[22] Charbonnel, E., C. Serre, et al. (2002) Effects of Increased Habitat Complexity on Fish Assemblages Associated With Large Artificial Reef Units (French Mediterranean coast). ICES Journal of Marine Science 58: S208-S213

[23] Hunter, W. R., M. Sayer. (2009). The Comparative Effects of Habitat Complexity on Faunal Assemblages of Northern Temperate Artificial and Natural Reefs. ICES Journal of Marine Science 66: 691–698.

[24] Reed, J.K. (2002). Deep-Water Oculina Coral Reefs of Florida: Biology, Impacts, and Management. Hydrobiologia 471: 43-55.

[25] “Artificial Reef.” Environmental Protection Agency. 5 October 2010. Web. 31 March 2013.[26] “Artificial Reef Program.” Florida Fish and Wildlife Conservation Commission, n.d. Web. 23 October 2012.

[27] Bohnsack, J.A., D. Sutherland. (1985). Artificial Reef Research: A Review With Recommendations For Future Priorities. Bulletin of marine Science 37(1): 11-39.

[28] Carter, A., S. Prekel. (2008) Benthic Colonization and Ecological Successional Patterns On A Planned Nearshore Artificial Reef System in Broward County, SE Florida. Proceedings of the 11th International Coral Reef Symposium, Ft. Lauderdale, Florida, 7-11 July 2008. Session number 24.

the science of the artificial reef program

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